A Novel Algorithm for Improving the Spectrum Efficiency of Non-Orthogonal Multiband CAP UVLC Systems

Abstract

Nowadays, how to further enhance the spectrum efficiency is one of the key technologies for band limited scenarios in underwater visible light communication (UVLC) systems. In this article, a novel subcarrier component extraction (SCE) with complex independent component analysis (ICA) algorithm is proposed in the non-orthogonal multiband CAP UVLC systems. With the proposed SCE-ICA algorithm, the non-orthogonal multiband CAP system can support a higher overlapping level in contrast to the conventional CAP scheme and therefore hold a higher spectral efficiency. In the simulation, varying degrees of performance enhancement is achieved in comparison with the conventional CAP scheme with different roll-off, compression factor (CF) and signal-noise ratio (SNR). Then, we first discover that in the simulated frequency-selective fading channels, moderate overlapping among subcarriers can achieve the best performance in system-level in contrast to the non-overlapping case. Moreover, the UVLC system experimental investigation of overlapping 2-CAP and 5-CAP scheme is carried out. The experiment demonstration shows that the utmost spectral efficiency enhancement of 40% and 18% are achieved compared with the non-compression CAP case and the conventional demodulation of the overlapping CAP case, respectively. Finally, with the low computational complexity of O(N), the proposed algorithm can be a potential candidate to handle the equalization of non-orthogonal multiband CAP schemes.